Motor controlling apparatus



Oct. 3, 1950 w. J. FIELD 23,275

MOTOR CONTROLLING APPARATUS Qr iginal Filed Nov. 6, 1944 2 Shams-Sheet 1 RUDD ER arm/172m YINVENTOI? WILLMM u. FIELD 4 gM %7401mn Oct. 3, 1950 w. J. FIELD MOTOR CONTROLLING APPARATUS Original Filed Nov. 6, 1944 2 sheets-sheet z IN VENTO)? WILL/19M J FIELD Reissued s. a, 1950 23,215 MOTOR cos-momma srraaa'rus William J. Field, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Original No. 2,480,125, dated August 30, 1949, Se-

rial No. 562,087, November 6, 1944. Application for reissue June 3, 1950, Serial No. 166,040

12 Claims.

Matter enclosed reissue spegiiication;

The present invention is concernedwith motor controlling apparatus and more particularly with apparatus in which a motor is operated in accordance with the amplitude of an alternating signal voltage.

It has been proposed to operate an alternating current motor in accordance with the magnitude and phase of an alternating signal voltage through the use of a discriminator circuit which is energized in one manner or the other, depending upon the phase of the alternating current. In such prior art motor controlling apparatus, it has been customary to energize the motor with the half wave rectifier output of the discriminator stage and to employ means for causing this halt wave output to simulate as nearly s possible the wave shape of an alternating voltage.

An object of the present invention is to provide a motor controlling apparatus in which a motor is energized with an alternating voltage varying in phase in accordance with the phase of an alternating signal voltage.

A further object of the present invention is to provide such an arrangement in which the electronic discharge devices of the discriminator stage are conductive during both half cycles of a complete cycle of the alternating voltage.

A still further object of the. present invention is to provide such an arrangement in which the motor may be reversibly operated in accordance with the phase of the signal voltage.

A still further object of the invention is to provide an arrangement of the type such as set forth in the previous objects in which the electronic discharge devices employed are of the gas filled type.

Another object of the invention is to provide an improved type of discriminator circuit in which the electronic discharge devices of the discriminator circuit are conductive during both half cycles so that the output of the discriminator circuit is an alternating voltage. 1

Other objects of the invention will be apparent from a consideration of the accompanying speciflcation, claims and drawing, oi which Figure 1 is a schematic showing of one form of my improved motor controlling apparatus shown as appliedto the positioning of the rudder of an aircraft, and

Figure 2 is a schematic showing of a modified form 01 my apparatus.

Referring tothe drawing for a more detailed understanding of the invention, the motor to be controlled is indicated generally by the reference numeral III. This motor comprises a, squirrel cage rotor Ii with which are associated a pair of field windings l2 and II. A condenser 14 is connected through conductorsl5 and I6 to the field windings l2 and I3. The function of condenser l4. as will be explained more fully later,

in heavy brackets appears in the original patent but forms no part or this matter printed in italics indicates the additions made by reissue is to cause the current through one or the other of the two field windings l2 and I3 to lead that through the other. The squirrel cage rotor II is connected through a, shaft schematically shown in the drawing and indicated by the reference numeral 11 to a gear train 16. The gear train. in turn, is connected through a shaft 19 to a rudder operator 20.

The motor as illustrated in the application is employed for positioning the rudder operator 20 in accordance with the signal received from a gyroscope 22.

The gyroscope 22 is adapted to position a movable contact 23 of a control potentiometer 24. The control potentiometer 24 in addition to the movable contact 23 comprises a resistance element 25 over which contact 23 is movable. The potentiometer 24 is associated with a further potentiometer 26 comprising a resistor 21 and a contact 28 s-lidable thereover. The two resistance elements 25 and 21 are connected together to form a Wheatstone bridge. The contact 26 is operatively connected through a shaft 29 to the rudder operator 20 and is thus positioned by shaft Ill. The potentiometer 26 functions as a rebalancing potentiometer.

Power is supplied to the system through a transformer 35. This transformer comprises a primary winding 36 and secondary windings 31 and 38. The primary winding 36 is connected to line wires 39 and 40 leading to a suitable source of power'mot shown). The secondary winding 38 is employed for supplying power to the Wheatsto-ne bridge and is connected by conductors 42 and-43 to the opposite terminals of resistor 21 of control potentiometer 26. These two terminals constitute the input terminals of the Wheats-tone bridge and contacts 23 and 2B the output terminals.

The output of the bridge is employed to control the operation of motor 10 through four gas filled discharge devices 44, 45, 46, and 41. These discharge devices are all similar in construction. The discharge device 44 comprises an electrically heated cathode 49, a control grid 56, a. shield grid 51 and an anode 52. Associated with the cathode 49 is a cathode heater 54 which is connected to any suitable source of power (not shown) such as an additional secondary of transformer 35. Similarly, the tube 45 comprises a cathode 56, a control grid 51, a. shield grid 58 and an anode 59. Tube46 comprises a cathode so, a control grid 6|, ashield grid 62 and an anode 63. Tube 41 includes a cathode 65, a control grid 66, a shield grid 61 and an anode 68. In

. each case, the cathodes have associated with them a cathode heater element.

of each. discharge device are enclosed within a gas filled envelope.

The voltage applied The elements to the control grids of 8 the various tubes is obtained from the control bridge through a transformer 10. This transformer comprises a primary winding 1| and four secondary windings 12, 18, 14, and 10. The upper terminal of secondary 1! is connected to control grid it through a conductor 11, a biasing battery 1!, a protective resistor 10 and a conductor 80. The other terminal of secondary 12 is connected through conductors 8| and II to the cathode 4|. Similarly, the lower terminal of secondary 13 is connected through a biasing'battery 84, a protective resistor 48 and a conductor 88 to the control grid 51. The upper terminal of secondary 18 is connected through a conductor 41 to the cathode 58 of the same tube 4!.

The upper terminal of secondary 14 is connected through a biasing battery N, a protective resistor II, and a conductor II to the control grid ll of tube 44. The lower terminal of secondary 14 is connected through conductor 02 to the cathode It. The lower terminal of secondary 15 is connected through conductor 44, biasing battery 95, protective resistor 94 and conductor I1 to the control grid ll. The upper terminal of the secondary 1! is connected through conductors BI and a! to cathode 44. Thus. each of the secondaries 12, 13, 14, and 1! is connected between the grid and cathode of one of the tubes in series with a biasing battery. In each case the polarity of the biasing battery is such as to tend to render the grid negative with respect to the cathode and is of suincient magnitude that in the absence of any other voltage the grid is maintained at a potential below the which the tubes are conductive.

The primary 1| of transformer 10 is connected to contacts 23 and 24 of the bridge by means of conductors I and "I. It will be recalled that contacts ll and it constitute the output terminals of the bridge.

Operation of Figure 1 The various elements are shown in the position they assume when the aircraft is in the desired attitude. Under these conditions, no one of the tubes 44 to 41 is conductive since in each case, the grid is biased negatively suiliciently to render the tube in question non-conductive. Consequently, no current is supplied to the motor field windings l2 and II and the motor is inoperative. Now let it be assumed that the aircraft departs from the desired course so that the gyroscope 22 is eirective to move the contact 23 to the right. The effect of this will be to cause contact 23 to be at a voltage different from that of contact 28 so that an unbalance voltage exists across the terminalsof the bridge. This unbalvalue at sequentlv, both the voltage of secondary 1I and that of biasing battery II are tending to drive grid ll negative with respect to the cathode so that the tube 41 is eflectively non-conductive. In the case of tube 44, the anode i8 is negative with respect to the cathode so that this tube is likewise non-conductive. In the case of tube .44, the anode is negative with respect tothe cathode so that the tube is non-conductive.

Let us now consider the polarities in connection with tube 45. It is to be noted that the anode 45 is connected to the end of the transformer secondary 31 which is positive during this half cycle with respect to center tap Ill. Moreover, the control grid 51 is connected to the lower end of secondary 13 which during this half cycle is positive with respect to the cathode. The positive voltage impressed upon grid 51 by secondary 13 thus tends to overcome the effect of biasing battery I4 so as to'render tube 4! conductive. As a result, a circuit is established to motor field winding I! as follows: from the upper terminal of secondary 31 through conductors ill and III, anode I9, cathode l6, conductors I41 and Ill, ileld winding l2 and conductor ill to the center tap ill of secondary 31. At the same time, current flows to field winding ll as follows: from the upper terminal of secondary 31, through conductors I05 and I", anode 59, cathode 58, conductors I01, I08 and I5, condenser 14, conductor [6, field winding l3 and conductor III! to the center tap of secondary 31.

Now let the conditions in the next half cycle be considered. Since the Wheatstone bridge is connected to the same source of power as the tubes 44 to 41, it will be obvious that the polarities will be reversed throughout. Thus, in the case of tube 41, the anode 68 will be negative with respect to the cathode so that this tube will be non-conductive. While the anode 83 will now be positive with respect to cathode III, the control grid 6| will also have its polarity reversed so as to be negative with respect to cathode 60. Hence, tube 46 will be non-conductive. In the case of tube 4!, the anode 5! will now be negative with respect to the cathode so that this tube will be non-conductive. As for tube 44, the anode 52 will be positive with respect to the cathode 49 and the grid 50 will now be positive with respect to ance voltage will in turn be applied to primary winding 1| of transformer 10. This in turn will cause a voltase to appear across the terminals of each of the secondaries 12 to 1|. The secondary windings 12 to 1! are so wound that during the half cycle in which the upper terminal of secondary 31 is positive with respect to the lower terminal, the upper terminals of secondaries 12 and 1! will be negative with respect to the lower terminals, while the upper terminals of secondaries 14 and 15 will be positive with respect to the lower terminals.

Considering the conditions during the half cycle in which the polarities mentioned in the last paragraph exist, the anode 08 of tube 41 is positive with respect to the cathode. However, the grid 68 during this half cycle is connected to what is the negative end of secondary 15. Conwindings l2 and II and during the other half.

cathode 49. Hence, tube 44 will be conductive during this half cycle with the result that current will flow through winding I! as follows: from the center tap I ll of secondary 31 through conductor illl, motor field winding l2, conductor I08, anode I2, cathode 48, and conductors 82 and I0! to the upper terminal of secondary 31. At the same time, a circuit will be established to field winding i3 as follows: from the center tap I l I of secondary 31 through conductor llii, field winding l3, conductor ll, condenser l4, conductors l5 and Ill, anode I2, cathode 49 and conductors 82 and III back to the upper terminal of secondaryv 31.

It is to be noted from the above that tube 4! is conductive during one half cycle and tube 44 during the other half cycle. This is due to the fact that with the bridge unbalanced in the direction which is being assumed, the alternating voltages applied to grids Ill and 51 are in phase with ,the anode voltages of the tubes 44 and 44. It is further to be noted that the current during one half cycle flows in one direction through cycle in the opposite direction. Thus, there is a iiow of alternating current through windings l2 and II. The alternating current flow through aaava winding II is through condenser ll so that the current through this winding leads that through winding l2. Thus, the motor rotates in a prede'- termined direction to cause operation of the rudder in a predetermined direction. The operation of this rudder is in such a direction as to tend to restore the plane to the course which the gyroscope 22 is trying to maintain. Furthermore, the operation of the motor in this direction moves contact 28 to the right with respect to resistor 21. The movement of the motor will continue until the position of contact 28 again corresponds to that of contact 23, at which time the bridge will again be rebalanced so as to eliminate the unbalance voltage. This will in turn cause the disappearance of an alternating voltage across the terminals of the-secondaries I2 to 15 with the result that tubes 44 to 41 all become nonconductive.

Thus, there will be a movement of the rudder in a direction such as to correct for the deviation of the craft irom the desired course in an amount corresponding to the extent of such deviation.

The deflection of the rudder as a, result of the foregoing action will cause the craft to gradually return to the desired course with the result that slider 23 is moved back to its original position. This causes slider 23 to be in a position to the left of slider 28 so as to result in an unbalance voltage appearing across the terminals of primary winding 1 l This unbalance voltage furthermore will be 180 out of phase with respect to the unbalance voltage previously considered. Thlls during the half cycle in which the upper terminal of secondary 31 is positive with respect to the lower terminal, the polarities of the voltages appearing across secondary windings 12 to 15 will be opposite to that indicated by the legends on the drawings.

Assuming the conditions just described, the relative polarities of the various elements of the tubes H to 41 will now be considered. In the case of tube 44, the cathode 49 will be positive with respect to the anode so that this tube will not be conductive. In the case of tube 45, while the anode is positive with respect to the cathode, the efiect of the voltage across secondary 13 will be to cause grid 51 to be more negative with respect to cathode 56 so that this tube will not be conductive. In the case of tube 46, the anode63 will be negative with respect to the cathode so that this tube will likewise not be conductive. In the case of tube 41, the anode 68 will be positive with respect to the cathode and the effect of the voltage across secondary I4 is to tend to cause grid 66 to be positive with respect to cathode 65. The eilect of the voltage across secondary 15 will overcome the biasing eiIect of the battery 95 so that tube 41 will be conductive and current will flow through winding l3 as follows: from the center tap I ll through conductor I I0, field winding l3, conductor H5, anode 68, cathode 65 and conductors l9 and H6 to the lower terminal of secondary 31. At the same time. a circuit will be established through field winding I2 as follows: from the center tap I ll through conductor i Ill, field winding I2, conductor i5, condenser l4, conductors l6 and H5, anode 68, cathode 65, and conductors 99 and I IE to the lower terminal of secondary 31. Now let the conditions during the next half cycle'be considered. Underthese conditions, the lower terminal of secondary 31 will be positvie with respect to the upper terminal and the polarities of the voltages across secondaries 12 to II will be the same as those indicated by the legends. Under these conditions. tube ll will be non-conductive because the grid II will be negative with respect to the cathode.

Tube 46 will be non-conductive because of the fact that the anode 59 will be negative with respect to the cathode I8. Tube 41 will be non-conductive because of anode 88 being negative with respect to cathode 65. Tube 46, however, will be conductive since during this half cycle the anode I is positive with respect to .the cathode and the voltage of grid 6| will likewise be positive with respect to the cathode 80. As a result, a circuit will be established to field winding is as follows: from the lower terminal of the secondary 31 through conductors lit and H1, anode I8, cathode 60, conductors Ill and H5, motor ileld winding l3 and conductor lit to the center tap Iii. A circuit will also be established to fleld winding l2 as follows: from the lower terminal of secondary 31 through conductors I I8 and H1, anode 63, cathode 6|), conductors H8, H5. and I6, condenser l4, conductor l5, field winding i2 and conductor iilito the center tap iii of secondary 31.

It will be observed from the above description that with the bridge unbalanced in the direction described, tubes 46 and I! are conductive during alternate half cycles. With these tubes conductive, moreover, current flows directly through field winding l3 while flowing through field winding l2'through condenser I. As a result an alternating current flows in both windings l2 and I3, the current through winding I 2 leading that through winding i3. It will be recalled that during the previous condition of unbalance the current through winding It leads that through winding i2. Thus the motor ID will rotate in the direction opposite to that previously considered to move the rudder back to its normal position. The slider 28 will likewise be moved back to the left, and this movement of the rudder will be continued until the positions of sliders 2i and 28 again correspond, at which time the rudder will be in substantially its original or neutral position. The ship will now be back on the desired course and the rudder in its normal position. The movement of contact 28 back to a position corresponding to that of contact 23 will eliminate the unbalance voltage appearing across the bridge, and hence eliminate any alternating voltage across the secondaries 12 to I5. Tubes 44 to 41 will hence again become non-conductive.

It is to be noted from the above description that with the apparatus of the present invention, I have provided a, discriminator arrangementin which alternating current is conducted to the motor field windings instead of half-wave rectified current. This results in much more desirable operation of the motor since the eil'ect of the direct current component. of a half-wave rectified current is detrimental to the proper operation of the motor.

' Species 01 Figure 2 The arrangement of Figure 2 difl'ers primarily from that of Figure 1 in the fact that it is possible to employ a, single secondary winding of half the winding to supply voltage to the anodes and cathodes of all four tubes. Another difl'erence between the circuit of Fi ure 2 and that of Figure l is that vacuum tubes are employed instead of the gas filled tubes of Figure -1. By reason of the use of vacuum tubes with their less critical sensitivity, it is possible to employ a self-biasing arrange- 1 ment for the grids and thus eliminate the need for biasing batteries 12, 64-, 66 and 65 of Figure 1.

In order to facilitate an understanding of the arrangement of Figure 2, identical reference numerals have been applied to those elements which correspond identically to elements of Figure 1. Furthermore, reference numerals one hundred higher have been applied to those elements which, while not identical to any elements in Figure 1, accomplish generally similar functions.

The arrangement of the motor ileld windings and the condenser I4 is identical to that of Figure 1 so, that no description thereof is deemed necessary. In order to avoid unnecessary duplication of description, the gear train, the rudder,

the gyroscope and the bridge have been omitted in Figure 2. It is to be understood, however, that motor II can be employed to operate such a rudder operator or any other similar device in :the same manner as in Figure 1. H of transformer 16 is not shown as connected to any signal voltage, it is to be understood that this can be connected to a Wheatstone bridge such as shown in Figure 1 or to any other suitable source of alternating signal voltage which is reversible in phase. The tubes in this species are designated by the reference numerals I44 to I41 and are preferably vacuum tubes. A typical tube which is suitable for this purpose is the type 2A3. Tube I44 comprises a cathode I46, a-control grid I56, and an anode I52. Associated with the cathode I46 is a cathode heater I54.conn.ected to any suitable energizing source (not shown). Tube I45 similarly comprises a cathode I55, a control grid I51 and an anode I56. The tube I46 has a cathode I66, a grid I6I and an anode I62. The tube I41 comprises a cathode l 65, a grid I66 and an anode I62. In each case, the cathode is provided with a cathode heater as in the case of tube I44.

Associated with the cathode I46 is a cathode biasing resistor 2III and a by-pass condenser 266.

Similarly, in connection with tube I45 is a' cathode biasing resistor 262 and a by-pass condenser 262. Associated with tubes I46 and I41, respectively, are cathode biasing resistors 264 and 255 which are by-passed by condensers 265 and 261 respectively.

The transformer I comprises a primary winding I26 which may be connected to any suitable source of power and a secondary winding I21. The primary winding I25 must be connected to a source of-power which is also associated with a means for supplying the signal voltage to primary 1I so that the voltage across primary H and that across primary I26 always has a phase relationship determined solely by the controlling eiIect. The upper terminal of secondary 12 is connected through a conductor III, and the biasing resistor 2II to the cathode I42. The lower terminal of secondary I2 is connected through conductor I11 to the grid I56. The upper terminal of secondary 12 is connected through conductor I21 to the control grid I51. The lower terminal of secondary" is connected through conductor I26 and biasing resistor 262 to the cathode I56. The upper terminal of secondary 14 is connected through conductors I62 and Ill and biasing resistor 264 to the cathode I62. The lower terminal of secondary 14 is connected through conductor I6I to the grid I6I. The upper terminal of secondary 15 is connected to control grid I56 through conductor 24 and the lower terminal is connected through conductor Ill and cathode biasing resistor 266 to the While the primary cathode I65. Thus, the voltages appearing across secondaries 12,12, 14 and 15 upon the occurrence of a signal voltage are impressed between the grids and cathodes of tubes I44 to I41, respectively. In each case, the connections include the cathode biasing resistor associated with the cathode of the tube in. question. This cathode biasing resistor functions in the usual manner to introduce a biasing voltage into the grid circuit by reason of the voltage drop occurring thereacross as a result of the anode current flowingthrough the tube. Thus, in the. absence of any signal voltage, the current flowing through .any tube circuit is very small due to the biasing effect of .the biasing resistors.

I Operation of Figure 2 Let it first be assumed that the phase of the signal voltage is such that during the half cycle in which the left-hand terminal of secondary I21 is positive with respect to the right-hand terminal, the polarities of the voltages across secondaries 12 to 15 correspond-to the legends appearing on the drawings. Under these conditions, tube I41 is not conductive since the anode I66 is negative with respect to the cathode I65. Tube I46 is not conductive since the effect of the voltage across secondary 14 is to render the grid III further negative with respect to the cathode I66. Similarly, tube I is non-conductive since the anode I59 is-negative with respect to the cathode. Tube I44 is conductive, however, since the anode I52 is positive with respect to cathode 12 is to raise the potential of grid I56 with respect to cathode I46. As a result, current flows to field winding I2 as follows: from the left-hand terminal of secondary I21 through conductor 2I6, motor field winding I2, conductors III and 2I2, anode I52, cathode I48, biasing resistor 26I and conductors 2I4,.2I5 and 2I6 back to the righthand terminal of secondary I21. At the same time, a circuit is also established to motor field winding I2 as follows: from the left-hand terminal of secondary I21 through conductor 2"], field winding I2, conductor l6, condenser I4, conductors I5, 2 and 2I2, anode I52, cathode I42,

resistor 26I and conductors 2I4, 2I5 and 2I6 to the right-hand terminal of secondary I21.

During the next half cycle, all of the polarities are reversed. Under these conditions, tube I41 is non-conductive since the grid I66 is now negative with respect to cathode I65. Similarly, tube I46 is non-conductive since the anode I62 is negative with respect to cathode I66 and tube I44 is non-conductive since the anode I52 is now negative with respect to the cathode. Tube I45 is conductive, however, since the anode is now positive with respect to the cathode and since the effect of the voltage across secondary 12 is such as to tend to raise the voltage of grid I51 with respect to cathode I56. Thus, current flows to field winding I2 through the following circuit: from the right-hand terminal of secondary I21 through conductors 2I6, M5 and 2I6, anode I55, cathode I56, cathode resistor 262, conductor 2, field winding I2, and conductor 2Il to the lefthand terminal of secondary I21. At the same time, a circuitis established to field winding II as follows: from the right-hand terminal of secondary I31 through conductors 2I5, III and III,

anode I59, cathode I56, biasing resistor 222, con- It will be seen from the above that'with a signal voltage of the phase being considered, tubes I44 and I45 are conductive during all half cycles to supply alternating current directly to field winding I2 and through the condenser I4 to field winding I3. The current through field winding I3 thus leads that through field winding I2 and the motor rotates in one direction.

When the phase of the signal voltage is reversed, the polarities of the voltages across secondaries 12 to 15 will likewise be reversed. As a result, during the half cycle in which the voltage of secondary I31 is that indicated by the legends, the grid I50 will be negative with respect to the cathode I43 so that tube I44 will be non-conductive. During the same hali' cycle, the anode I5! is negative with respect to the cathode I56. In other words, the voltages impressed :upon the grids I50 and I51 are now out of phase with the anode voltages impressed on the two tubes I44 and I46. Under these conditions, the anode I68 will be negative with respect to the cathode I65 so that tube I41 will not be conductive. Tube I46 will, however, be conductive since the anode will be positive with respect to the cathode and the effect of the voltage across secondary 14 tends to raise the potential of the grid with respect to the cathode. -As a result, a circuit will be established to field winding I3 as follows: from the left-hand terminal of secondary I31 through conductor 2), field winding I3, conductors 2" and Ill], anode I63, cathode I60, biasing resistor 264, and conductors I93, 226 and 2I6 to the other terminal of secondary I31. At the same time, an energizing circuit will be established to field winding I2 as follows: from the left-hand ter-' mine] of secondary I31 through conductor 2III, field winding I2, conductor I5, condenser I4, conductors I6, 2I8 and 2I9, anode I63, cathode I60, biasing resistor 204, and conductors I33, 220 and 2I6 to the right-hand terminal of secondary I31.

During the next half cycle, the polarities of the voltages across secondaries 12 to 15 will be the same as indicated in the drawing, while the voltage across the secondary I 31 will be opposite to that indicated by the legends. As a result, tubes I44 and I46 will be non-conductive by reason of the anodes being negative with respect to the cathodes. Tube I45 will be non-conductive because the voltage applied by secondary 13 will tend to drive grid I51 negative with respect to cathode I56. However, the tube I41 will be conductive since the anode is now positive with respect to the cathode and the voltage applied by secondary 15 tends to raise the potential of grid I66 with respect to cathode I65. As a result of 'tube I41 being conductive, a circuit will be established to field winding I3 as follows: from the right-hand terminal of secondary I31 through conductors 2I6, 220, I93. and 222, anode I68, cathode I65, biasing resistor 206, conductors 223 and 2I3, field winding I3 and conductor 2IIl to the left-hand terminal of secondary I31. At the same time, a circuit will be established to field winding I2 as follows: from the right-hand terminal of secondary I31 through conductors 2I-6, 220, I33 and 222, anode I63, cathode I65, cathode resistor 266, conductors 223, 2; and I6, condenser I4, conductor I5, field winding I2 and conductor 2III to the left-hand terminal of secondary I31.

Thus again, both windings I2 and I3 areenergized during opposite half cycles in opposite directions as a result of the alternative conductivity of tubes I46 and I41. In this case, field winding 10 I3 is energized directly whereas field winding I2 is energized through condenser I4 sothat'the current through the latter leads that through the former, thus causing operation of motor II. in the opposite direction. It is to be noted that with the species of Figure 2. as with the species of Figure 1, a motor III is supplied with a full alternating current as distinguished lrom a half-wave rectified current such as is the common practice in'connectio'n with discriminator circuits. Furthermore, this is accomplished in the arrangement of Figure 2 with the use of a single secondary winding with no center tap, this secondary winding being connected in the anode circuit oi! all four tubes.

Conclusion I It will be seen that I have provided a new and improved motor controlling apparatus by which current power source, [a] an alternating current motor, a pair of electron tubes, each having an anode, a cathode, and a. control element, first circuit connections connecting one terminal 'of said source [being connected] to the cathode of the first tube and to the anode of the second tube, further circuit connections electrically connected to said motor and connecting [and] the anode of the first tube and the cathode of the second tube [being connected to one terminal of said motor, the other terminal oi saidmotor being connected] to the other. terminal of said source, means including a main controller for producing an alternating control voltage reversible in phase and variable in magnitude dependent upon the direction and magnitude of change of said main controller said control voltage being of the same frequency as said source, and means arranged to supply said control voltage in phase opposition [a variable potential] to thecontrol elements 01 [each 01'] said tubes of the same frequency assaid source, and of opposite phase on the respective tubes] so that when said control voltage is of one phase, said tubes are conductive on opposite half cycles to supply a full wave alternating current to said motor and when said control voltage is of the opposite phase, neither tube is conductive. v

2. In control apparatus for supplying alternating current to a. load means in one manner or another, a source of alternating signal voltage, reversible in phase in accordance with the condition of a main controller, a source 01 alternating power, and means for supplying alternating current from said last named source to said load means in the one manner or the other depending upon the phase of said signal voltage, said means comprising two pairs of electronic discharge devices each having an anode. a cathode. and a control element. both pairs of devices being connected between said load means and said source of power, the anodes and cathodes of'the 11 discharge devices oi eachpair being reversibly connected together so as to be conductive durin alternate hali cycles, and means for applying voltages to the control elements of said discharge devices related to the signal voltage in such a manner that the devices oi one or the other 01' said pairs of devices are energized during alternate hali cycles, the pair which is energized depending upon the phase of said signal voltage, said last named means comprising a transformer having a primary winding and tour secondary windings, said primary winding being connected to one or the other oi said motor paths, said means including two pairs of electronic discharge devices each having an anode, a cathode, and a control element, each pair oi devices being connected in series with one 01' said motor paths, the anodes and cathodes of the discharge devices oi each pair being reversibly connected together so as to be conductive during alternate hali cycles, and means for applying voltages to the control elements oi said discharge devices related to the signal voltage in such a manner that one or the other of said pairs of discharge devices is energized depending upon the phase oi said signal voltage.

4. In motor control apparatus, a reversible alternating current motor to be controlled and having two paths therethrough, said motor being operative in one direction or the other dependent upon which oi said paths is energized, a source of alternating signal voltage reversible in phase in accordance with the condition of a main controller, a source of alternating power and means ior selectively supplying power from said source to one or the other 01 said motor paths, said means including two pairs of electronic discharge I devices each having an anode, a. cathode, and a control element, each pair of devices being connected in series with one of said motor paths, the anodes and cathodes of the discharge devices of each pair being reversibly connected together so as to be conductive during alternate hali cycles, and means for applying voltages to the control elements oi said discharge devices, the voltages applied to the control elements of the devices of either pair being reverse in phase with respect to each other and with respect to those applied to the control elements of the devices of the other pair so that the devices of one pair or the 12 and means for selectively controlling the connections between said source and said two motor paths, said means including two pairs of electronic discharge devices each having an anode, a cathode, and a control element, each pair of devices being connected in series with one oi said motor paths. the anodes and cathodes oi the discharge devices oi each pair being reversibly connected together so as to be conductive during alternate hali cycles, and means for applying voltages to the control elements 01' said tubes related to the signal voltage in such a manner that one or the other of said pairs of tubes is energized depending upon the phase oi said signal voltage.

6. In motor control apparatus, a reversible alternating current motor to be controlled and having two paths therethrough. said motor being operative in one direction or the other dependent upon which 0! said paths is energized, a source of alternating signal voltage reversible in phase in accordance with the condition of a main controller, a source oi alternating power having two portions connected in phase opposition and each connected in series with one oi said paths, and means for selectively controlling the connections between said two portions and said two motor paths, said means including two pairs of electronic discharge devices each having an anode, a cathode, and a control element, each pair 0! devices being connected in series with one oi said motor paths, the anodes and cathodes oi the discharge devices of each pair being reversibly connected together so as to be conductive during alternate hali cycles, and means for applying voltages to the control elements oi said tubes related to the signal voltage in such a manner that one or the-other oi said pairs oi tubes is energized depending upon the phase 01 said I signal voltage.

'1. In control apparatus for supplying alternating current to a load means in either oi two manners, a source of alternating signal voltage reversible in phase in accordance with the condition of a main controller, a source of alternating I power, and means ior supplying alternating current from said last named source to said load means selectively in one or the other. oi said two manners depending upon the phase of said signal voltage, said means comprising two pairs of electronic discharge devices each having an anode, a cathode, and a control element, both pairs of devices being connected between said load means and said source of power, the anodes oi the discharge devices of each pair being oppositely connected to said source so as to be conductive during alternate hali cycles and oppositely connected to said load means so that the current through said load means reverses during alternate hali cycles, and means ior applying voltages to the control elements of said discharge devices related to the signal voltage in such a manner that the devices oi one or the other of said pairs oi devices are energized during alternate hali cycles, the pair which is energized depending upon the phase 01 said signal voltage. I I

8. For control of a motor having three terminals, and which runs in one direction when current is supplied to the first and second terminals, and in the other direction when current is supplied to the second and third terminals, a system including a source oi alternating current .power, a connection between one terminal oi said source and said second terminal of the motor, a first and second electron tube, each having an anode,

a cathode. and a control element, a connection between said source, the cathode of said first tube and the anode of the second tube, a connection between the first terminal 01' the motor, the anode of said first tube and the cathode of the second tube, a third and fourth electron tube, each having an anode, a cathode, and a control element, a connection between said source, the cathode of said third tube and the anode of the fourth tube, a connection between the third terminal of the motor, the anode of the third tube and the cathode of the fourth tube, means arranged to supply a variable control voltage between the control element and cathode of each of the first and second tubes, of the same frequency as said source and of opposite phase on the respective tubes, and means arranged to supply a variable control voltage between the control element and cathode of each of the third and fourth tubes, of the same frequency as said source and of opposite phase on the respective tubes.

9. For control of a motor having a pair of windings relatively displaced in space phase, having a common terminal, and each having a free terminal, a. system including a center-tapped alternating current power supply, a connection between the center tap of said power supply and the common terminal of said motor windings, a connection from one terminal 01' the power supply to the free terminal of one motor winding, an

electron tube having anode and cathode elements interposed in series with the last mentioned connection, means rendering said electron tube conductive upon the application to said means of an alternating control voltage exceeding a predetermined magnitude and having a given phase polarity with respect to that of the power supply, a connection from the other terminal of the power supply to the free terminal 01' the other motor winding, a second electron tube, having anode and cathode elements interposed in series with the last mentioned connection means rendering said electron tube conductive upon the 7 application to said means of an alternating control voltage exceeding a predetermined magnttude and having a phase polarity with respect to that oi the power supply which is the opposite of that for the first mentioned control voltage, and a phase shifting device connected between the free terminals of the motor windings.

10. In control apparatus for supplying alternating current to a load means in one manner or another, a source of alternating signal voltage reversible in phase in accordance with the condition of a main controller, a source of alternating power, and means for supplying alternating current with substantialy no unidirectional component from said last named source to said load means in the one manner or the other depending upon the phase of the signal voltage, said means comprising two pairs of electronic discharge devices each having an anode, a cathode, and a control element. each pair of devices being so connected between said load means and said source of power in series with said source of power that when thedevices oi the pair are conductive current fiows through said load means in opposite directions during alternate half cycles, and means for applying alternating voltages to the control elements of said discharge devices related to the signal voltage in such a manner that the devices of one or the other of said pairs 01' devices are energized during alternate halt cycles, the pair 14 which is energized depending upon the phase of said signal voltage with respect to said source of power.

11. In control apparatus for supplying alternating current to either one or the other of two portions of a load means, a source of alternating signal voltage reversible in phase in accordance I with the condition of a main controller, a source of alternating power, and means for supplying alternating current with no appreciable unidirectional component from said last named source to one or the other of said two portions of said load means depending upon the phase of the signal voltage, said means comprising two pairs of electronic discharge devices each having an anode, a cathode, and a control element, each pair of devices being so connected between said source 01 power in series with said source of power and one of said-two portions of said load means that when the devices of the pair are conductive current flows through the associated portion of the load means in opposite directions during alternate half cycles, and means for applying alternating voltages to the control elements of said discharge devices related to the signal voltage in such a manner that the devices of one or the other of said pairs of devices are energized during alternate half cycles, the pair which is energized depending upon the phase of said signal voltage with respect to said source of power.

12. In a motor control circuit, an alternating current power source, [a] an alternating current motor, a pair of gas filled tubes, each having an anode, a cathode, and a. control element, first circuit connections connecting one terminal of said source [being connected] to the cathode of the first tube and to the anode of the second tube, further circuit connections electrically connected to said motor and connecting the anode of the first tube and the cathode of the second tube [being connected to one terminal of said motor. the other terminal of said motor being connected] to the other terminal of said source, means including a. main controller for producing an alternating control voltage reversible in phase and variable in magnitude dependent uflm the direction and magnitude of change of said main controller, said controller being of the same REFERENCES CITED The following references are of record in the file of this patent or the original patent:

UNITED STATES PATENTS Name Date Brown Apr. 17. 1934 Chambers Apr. 11, 1939 Harrison Dec. 3, 1940 Conklin July 1, 1947 Edwards Aug. 12, 1947 Number 

